Siamese Algae Eater Stats InfographicThe Siamese algae eater, also known as crossocheilus oblongus, is a common freshwater fish with a reputation for scarfing down algae.

They are endemic to the rivers of Southeast Asia in places such as Thailand, the Malay Peninsula, Chao Phraya, and Mekong. Many aquarists fancy them because of their role in regulating the growth of algae in water bodies and overall water health.

Siamese algae eater care requires some work. Our article will give you in-depth information on all you need to know about the Siamese algae eater, from appearance, diet, and care to behavior, lifespan, and breeding.

Siamese Algae Eater Stats

Common Names True Siamese algae eater, SAE
Family Cyprinidae
Origin Southeast Asia
Care Level Easy
Temperament Peaceful and social
Average Size 6 inches
Lifespan 10 years
Breeding Egg laying
Diet Omnivore
Tank Level Bottom Dweller
Minimum Tank Size 20 gallons
Temperature 75 to 79°F
Hardness 5 to 20 KH
pH 6.5 to 8.0
Growth Rate Mature within 6 months to 2 years


Siamese algae eaters are endemic to Southeast Asia’s small streams and rivers. You can find them in Thailand, the Malayan Peninsula, Mekong, etc. Sometimes, you can find them in flooded forests with extremely low pH and negligible water hardness, feeding on the algae prominent in these ecosystems.

In the wild, they prefer fast-moving waterbodies with substrates such as pebbles, sand, and boulders. Thanks to their sucker-like mouths, they can fasten themselves to the smooth surfaces in their habitat and go quickly with the tide.

The Siamese algae eater is regarded as the most efficient algae eater. It is peaceful, not so large, and a great tank cleaner! As the name suggests, it feeds on coarse algae, a task not many fish can manage. Let’s learn more about this fish, including how it looks.

– What Do Siamese Algae Eaters Look Like?

Siamese algae eater in aquariumSiamese algae eaters have long, narrow bodies that are usually silver or pale gray. A black stripe runs lengthwise down their body from head to tail. This stripe fades against the water background and serves as camouflage to protect the fish from predators. It is essential to note this black stripe isn’t perfectly straight. Looking at the fish from an angle, you may notice a brighter colored line.

They have caudal fins that are nearly transparent, and unlike most aquarium fish, they lack a swim bladder. Due to this, they always have to be in motion, or they sink to the bottom. On their under lip, you will discover a pair of barbs.

Most people mistake Siamese algae eaters for their cousins, the Siamese flying fox, which is not as helpful in the aquarium.

– How to Tell a Siamese Algae Eater From a Siamese Flying Fox

Although commonly mistaken, it is possible to distinguish between these two fish species. One difference is that the fins of the Siamese algae eater are almost transparent, save for a speck of black that reaches its caudal fin. The Siamese flying fox, on the other hand, has orange-yellow tints on its fins.

Another difference is that the Siamese algae eater has more of a shark-like appearance. However, it has a peaceful demeanor. Finally, the flying fox has a distinctive light gold band with telltale black stripes that run along its sides.

– Size

The full-grown Siamese algae eater can grow up to 6 inches (16cm) when adequately cared for. There have been rare cases where the fish grew past this 6-inch mark. It has been observed that the fishes that grew bigger were raised in a bigger tank, had an ideal tank environment, and received proper nourishment.

– Sexual Dimorphism

Siamese algae eaters have rather poorly pronounced sexual differences. For now, there are no major distinctive features that can help you differentiate between the male and a female Siamese algae eater. However, if you pay keen attention, you will observe that female Siamese algae eaters have bigger abdomens than their male counterparts. The more prominent belly caters to breeding.

– Lifespan

Siamese algae eater lifespan in captivity is around 10 years because it is unlikely for this species to survive for this long in the wild. Therefore, to enjoy your fish, you must pay attention to its preferred environment, diet, etc.

– Behavior

Thanks to the Siamese algae eaters’ shark-like appearance, most people conclude the Siamese algae eater aggressive. On the contrary, they are very peaceful, active fish constantly on the move thanks to the absence of a swim bladder. The lack of swim balance means that this fish is not buoyant and prefers the bottom layer.

They are incredibly social and prefer shoaling in groups of at least 5 Siamese algae eaters.

Other exciting behaviors observed include:

  • They will sink once they stop moving.
  • Siamese algae eaters attach themselves to the walls of their environment via specialized mouth organs (suckers).
  • Siamese algae eater at rest propels itself up using its pectoral fin.

– Can I Raise a Single Siamese Algae Tetra?

Yes, you can raise a Single Siamese algae tetra. However, because they are schooling fish, it is recommended that you raise them in groups of at least 5. In pretty large groups like this, you will see more natural fish behaviors. As a plus, you will also get to observe exciting interactions and behaviors between the communities of Siamese algae tetra.

– Benefits of Raising this fish

Unlike most other fish species, the Siamese algae eater is an excellent addition to your tank for maintaining tank cleanliness. So because they eat up algae, they help keep the algae within the tank to an accepted healthy range.

Another advantage of the Siamese algae eater is that they are relatively low maintenance; they do not need extensive care to thrive. So once you meet their basic needs, they pay you back by improving the water quality in your tank.

The last benefit on the list is aesthetics. Siamese algae eaters are beautiful; maybe not as gorgeous as the African cichlid, but still, they are beautiful. So, they add color and spice to your aquarium.

Siamese Algae Eater Care

Siamese algae eater in planted aquarium

Before you commit to caring for Siamese algae eaters, you should know how to keep them healthy and what diseases to watch out for. They are beautiful fishes for beginner aquarists because by showering them with basic care, you can get them to thrive.

With proper care and diet, Siamese algae eaters can live for as long as 10 years in captivity. So, enough said, let us delve into how to care for your Siamese algae eater.

– Tank Set-Up

One of the stumbling blocks to caring for the Siamese algae eater is setting up its tank correctly. Questions like “What do I need to set up the ideal tank for this fish?”, “Should I keep just one or more?” are common with beginners.

A Siamese algae eater tank size of 20 to 30 gallons, with a close-fitting hood or cover, is essential. Other things you’d need include lighting, a heater, filter, substrate, plant decorations, and a water test kit. Whatever you do, ensure that their tank set-up is as close to their natural environmental conditions as possible.

Let’s discuss the basic requirements of this fish in detail.

1. Tank Size and Shape

The best tank for Siamese algae eaters is one that takes into account their swimming pattern as well as their size. Since they are very active and love jumping, it is advised you get a tank of not less than 20 gallons, preferably one with a hood or cover.

If you intend to raise more than one of these fish breed, you will need to add an extra 10 gallons for every other fish you add. Essentially, this means that if you want to raise 4 algae eaters, you will need 20 gallons for the first fish and an extra 10 gallons each for the other 3 fish. So in total, you will need a 50-gallon tank to raise 4 Siamese algae eaters.

2. Water Parameters

Siamese algae eaters are not sensitive to the level of hardness in the water; they adjust well to a wide range of hardness levels. However, there is one condition. The parameters must be consistent.

They prefer water pH within the range of 6.5 and 8.0 but can tolerate acidic conditions of up to 6.0. The most limiting factor is the Siamese algae eater temperature. They thrive at temperature conditions that are just under tropical conditions, i.e., 75 to 79℉. To keep the temperature relatively constant, you will need a water heater.

3. Substrate

The best substrate for a Siamese algae eater is one that is easy for you to clean up and doesn’t hurt the fish’s abdomen or delicate barbels. Soft substrates like sand and aquatic soils are best because they lack any of the jagged ends that rocks have.

Alternatively, you can use a blend of small round pebbles and large rocks with smooth surfaces. But you should never use aquarium gravels with rough edges.

4. Filtration and Aeration

While Siamese algae eaters do well in tanks set up like a riverscape with wavemakers and strong currents, they do not need such high flow rates.

Your Siamese algae eater will thrive in a tank with well-filtered and pristine water. Bear in mind that they do not like stagnant water and love water with high oxygen levels. You will need a solid filter. An excellent canister or HOB system is recommended.

5. Lighting

Siamese algae eaters do great in tanks with mixed lighting conditions, i.e., lighting does not play an essential role in their survival. Both bright and scattered light works well for these fish. They do well with 12 hours a day of moderate to low light. Thus, you must pay attention to the light requirements of the plants in the tank.

6. Tank Decoration

Plants are a great addition to your tank; not only do they act as areas of shelter for the fish, but they also help keep the water cleaner and more oxygenated.

One tip is to use plants that proliferate to cater for when your fish gets hungry and feeds on the plants. Fast-growing plants can handle being snacks for the fish and quickly get back to their original size and height.

Other necessary tank decorations like small tunnels, hollowed-out logs, and swim-in-hide-outs are perfect for the Siamese algae eaters’ tank. They provide vital shade and hiding spots to ensure your fish experiences as little stress and swimming fatigue as possible. Also, with these rocks and hollowed-out logs, you can create ample surfaces for algae and biofilm to grow so your fish can consume them.

Tank Mates

Siamese algae eater compatibility has a lot to do with their temperament and behavior. Generally, they are peaceful, so there is a long list of tank mates they are compatible with. Thanks to this, they are great candidates for a community tank.

It is important to note that since Siamese algae eaters spend all their time at the bottom of the aquarium, you must choose tank mates that will not try to bully them. Like the Redtail sharks, many bottom-dwellers are territorial, harassing other species in a bid to protect their territory. Thus, it would help if you avoided them and instead choose peaceful bottom dwellers like Corydoras.

Also, while fish from other water areas may not compete for territory with the Siamese algae eater, their temperament and size should be taken into account. So that rules out Cichlids. It is good to remember that your choice of tank mate is not restricted to just fish species; you can add other animals that eat algae.

In summary, these are a few of the possible tank mates for your Siamese algae eaters:

– Tank Mates To Avoid

Siamese algae eaters are very active and social. However, they may nip at fish that swim slowly or those with long fins.

Thus, as a rule of thumb, you cannot pair them up with slow-moving fish, aggressive or semi-aggressive fish like:

  • Cichlids
  • Redtailed sharks
  • Tiger barbs


Breeding the Siamese algae eater in captivity can be pretty tricky, especially when it is not in a controlled fish farm setting. It is so far not known if anyone in the US has succeeded in breeding this fish species. Part of this lack of success arises from the fact that little or nothing is known about their breeding and spawning behaviors.

However, there are reports that some Siamese algae eaters have been successfully bred in captivity in Asia. These reports claim these breeders used artificial hormones to induce the fish to spawn; however, any details on the use of hormones are unknown. Even if the hormones work, the reality is that they are not things that are readily accessible by the average home aquarist.

The Siamese algae eaters you see on sale at pet stores are bred either in fish farms or caught in the wild. It is pretty unrealistic to expect your Siamese algae eater to spawn in your tank.


Like most fish species, the reticulated Siamese algae eater needs to be placed on a proper diet of high-quality food to maintain health and extend their lifespan. They are omnivores and, as such, are not picky eaters. They will eat anything you give to them, from dead insects to dead fish and, of course, plant matter.

In the wild, Siamese algae eaters feed on a variety of algae-like Periphyton and phytoplankton. They also eat dead fish and insects that they come across. For best results in captivity, you will need to mimic their conditions in the wild as much as possible.

Here are a few things you can feed your Siamese algae eater with:

– High-quality Commercial Diet

These sinking diets, such as Spirulina pellets and sinking algae wafers, help distract the fish in the upper regions.

– Fresh Veggies

Blanched vegetables like peas, cucumbers, and spinach are great substitutes for algae wafers.

– Proteins

It is essential to strike a balance; thus, once a week, it is advised that you add protein treats such as bloodworms, mosquito larvae, daphnia eggs, and brine shrimp.

Juvenile Siamese algae eaters typically consume more algae than the adults who desire a protein-based diet. Try to strike a balance so that there is no overload of no one food type.

– Frequency of Feeding

Throw in just enough food for the fish to finish within a few minutes. Avoid overfeeding your fish as much as possible because it can have disastrous implications for the fish.

Underfed fish, on the other hand, tend to nibble on other plants within the tank. So the best advice is to feed them with small portions of food several times a day.

Overfeeding this fish species may cause them to stop consuming algae in favor of the other meals you give them in excessive amounts. Among others, this is one reason why you should restrict their portions to small quantities, which they can gulp down in minutes.

Common Diseases

On average, Siamese Algae Eaters are healthy fish that do not have a lot of species-specific diseases. However, they are like all other aquarium species and are sensitive to water parameters and quality within their tank. Lack of pristine water and poor water conditions predispose Siamese algae eaters to stress and diseases.

Although they do not have species-specific diseases, they are still susceptible to the common issues that plague other freshwater fish species. These diseases give clear signs and can easily be treated.

Let’s take a look at some of these diseases.

1. Constipation and Bloating

These are two diseases that plague most Siamese algae eaters. They result from a diet rich in protein, i.e., when the diet contains more protein than any other component. To prevent these diseases, step up the intake of fresh vegetables and plant-based foods.

We recommend that you feed them a mixture of food that includes protein and natural plants (vegetables). You need to balance the amount of protein you give your fish as excess can make the fish less inclined to feed on algae. Another option is to supplement the live food and flakes with commercial foods.

2. Ich

Ich is one of the parasitic diseases that affect Siamese algae eaters. It is characterized by telltale white spots on the body of the fish.

Others symptoms of Ich include strange swim patterns, a sharp decline in appetite, and lethargy. Regular water change, the diet of high-quality food, and optimum water conditions help keep this disease at bay. Raise the temperature of the water to treat the affected fish; over-the-counter antibiotics also help to take care of this disease.

– Ways To Prevent Diseases

Like in other aquarium species, you can prevent the spread of disease in your tank by following these steps:

  • Quarantine new fish and plants before adding them to your established tank.
  • Disinfect all your equipment thoroughly.
  • Maintain excellent water conditions and parameters (pH, temperature, hardness, etc.).
  • Ensure that your fish are fed a high-quality, balanced diet.
  • Avoid overfeeding your fish.
  • Look out for fish showing symptoms of infection and immediately isolate them from the others in the tank.


  • Siamese algae eater also known as crossocheilus oblongusSiamese algae eaters are fun, social community fish that have a reputation for scarfing down algae.
  • They are low maintenance and thrive with the slightest care; hence, they are perfect for beginner aquarists and enthusiasts.
  • With proper care, Siamese algae eaters can live for as long as 10 years

We know that you have gleaned an in-depth understanding of Siamese algae eaters as a fish species and ways to ensure that they thrive. We’d love to get feedback or questions regarding your setup. Do drop your comments.

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